Display device

ABSTRACT

A display device includes: a light source; a display panel capable of receiving the light from a first surface side and transmitting the light to a second surface side; and a light guiding member. The display panel is inclined with respect to an orthogonal plane orthogonal to an optical axis of the light. The light guiding member has an output surface framed by an output port of the light and inclined with respect to the orthogonal plane. An inclination direction of the display panel is identical to an inclination direction of the output surface. The light guiding member has such a shape that a distance between inner surfaces of the light guiding member and the optical axis increases toward the first surface side from the light source side, and the inner surfaces opposing each other at positions orthogonal to the optical axis are not uniform in curvature.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority from Japanese PatentApplication No. 2018-165084 filed on Sep. 4, 2018 and InternationalPatent Application No. PCT/JP2019/030750 filed on Aug. 5, 2019, theentire contents of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device.

2. Description of the Related Art

What-is-called head up displays (HUD) that project an image onto amember having translucency, such as glass, have been known (for example,Japanese Patent Application Laid-open Publication No. 2014-178368).

The HUD projects an image by causing a display panel to transmit lightfrom a light source. The display panel can however reflect lightincident from an output surface side. When the light from the lightsource and the reflected light are superimposed with each other, a ghostcan be viewed due to multiplex projection of the same image.

In order to prevent superimposition of the light from the light sourceand the reflected light, there is a method in which the display panel isarranged so as to be inclined with respect to an output direction of thelight from the light source. Unfortunately, only inclination of thedisplay panel with respect to the output direction of the light from thelight source causes the image to have luminance unevenness anddistortion in the inclination direction, resulting in reduction indisplay quality.

For the foregoing reasons, there is a need for a display device capableof achieving both of restraint of the occurrence of a ghost andimprovement in display quality.

SUMMARY

According to an aspect, a display device includes: a light sourceconfigured to emit light; a display panel capable of receiving the lightfrom a first surface side and transmitting the light to a second surfaceside; and a light guiding member extending to the first surface side ofthe display panel from the light source and reflecting the light to thedisplay panel. The display panel is inclined with respect to anorthogonal plane orthogonal to an optical axis of the light, the lightguiding member has an output surface framed by an output port of thelight and inclined with respect to the orthogonal plane, and aninclination direction of the display panel with respect to the opticalaxis is identical to an inclination direction of the output surface withrespect to the optical axis. The light guiding member has such a shapethat a distance between inner surfaces of the light guiding member andthe optical axis increases toward the first surface side from the lightsource side, and the inner surfaces opposing each other at positionsorthogonal to the optical axis are not uniform in curvature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the main configuration of adisplay device according to an embodiment;

FIG. 2 is a block diagram illustrating an example of the systemconfiguration of a display unit;

FIG. 3 is a circuit diagram illustrating an example of the configurationof a drive circuit configured to drive pixels in the display unit;

FIG. 4 is a schematic view of the display device capable of localdimming;

FIG. 5 is a diagram illustrating aspects and arrangement of the displayunit, a light source unit, a light guiding unit, and a diffusion plate;

FIG. 6 is a perspective view of the light guiding unit;

FIG. 7 is an X-Z plan view of the light guiding unit;

FIG. 8 is an X-Y plan view of the light guiding unit;

FIG. 9 is a cross-sectional view cut along line J-J in FIG. 8;

FIG. 10 is a cross-sectional view cut along line K-K in FIG. 8;

FIG. 11 is a Y-Z plan view of a light guiding member;

FIG. 12 is an X-Z plan view of the light guiding member;

FIG. 13 is an X-Z plan view of the light guiding member;

FIG. 14 is a perspective view of a light source; and

FIG. 15 is a schematic descriptive diagram for explaining a relationbetween angles of a plate surface of the display unit, an outputsurface, and a plate surface of the diffusion plate, and a shape andluminance distribution of an image output from the display device.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings. The disclosure is merely an example, andappropriate modifications within the gist of the disclosure at whichthose skilled in the art can easily arrive are encompassed in the rangeof the present disclosure. To further clarify the description, widths,thicknesses, shapes, and the like of various parts may be schematicallyillustrated in the drawings as compared with actual aspects thereof.They are however merely examples and do not limit interpretation of thepresent disclosure. In the present specification and the drawings, thesame reference numerals denote components similar to those describedbefore with reference to the drawing that has been already referred, anddetail explanation thereof can be appropriately omitted.

In this disclosure, when an element is described as being “on” anotherelement, the element can be directly on the other element, or there canbe one or more elements between the element and the other element.

FIG. 1 is a schematic diagram illustrating the main configuration of adisplay device 1 according to an embodiment. The display device 1includes a light source unit 6 functioning as a light source device, adisplay unit 2 configured to output an image using light L from thelight source unit 6 as a light source, and a diffusion plate 9 providedbetween the display unit 2 and the light source unit 6, for example. Thelight L emitted from the light source unit 6 is diffused by thediffusion plate 9 and reaches the display unit 2, so that a part or allof the light L passes through the display unit 2, is reflected bymirrors M and a windshield FG, and reaches a user H to be recognized asan image VI in a sight of the user H. That is to say, the display device1 in the embodiment functions as a head-up display (HUD) using themirrors M and the windshield FG. Although the windshield FG is, forexample, a windshield of a vehicle, it is sufficient that the windshieldFG is a member having translucency and located on the line of sight ofthe user H.

In the embodiment, plate surfaces of the display unit 2 and thediffusion plate 9 are inclined with respect to an optical axis IL (seeFIG. 9 and other figures) of the light L traveling toward a plate mirrorM1 from the light source unit 6. An optical axis of external light SLentering the display unit 2 through the mirrors M can be directed to adirection differing from the optical axis IL of the light L due to theinclination of the display unit 2 with respect to the optical axis IL.Generation of a ghost due to the external light SL reaching to the userH through the mirrors M again after being reflected by the display unit2 can be therefore be hindered.

Although in FIG. 1, the light L after passing through the display unit 2is guided by two mirrors M including the plate mirror M1 and a concavemirror M2, the number of mirrors may be one or equal to or more thanthree.

Next, the display unit 2 is described. FIG. 2 is a block diagramillustrating an example of the system configuration of the display unit2. FIG. 3 is a circuit diagram illustrating an example of theconfiguration of a drive circuit configured to drive pixels Pix in thedisplay unit 2. The display unit 2 in the embodiment is a transmissiveliquid crystal display that outputs an image using the light L as thelight source. The display unit 2 is, for example, a transmissive liquidcrystal display and includes an image output panel and a drive element3, for example, a display driver integrated circuit (DDIC).

The image output panel includes, for example, a translucent insulatingsubstrate, such as a glass substrate, and has a display region 21provided on the surface of the glass substrate and formed by arranging alarge number of pixels Pix including liquid crystal cells in a matrix(row-column configuration). Each pixel Pix includes a plurality of subpixels Vpix (see FIG. 3). The glass substrate includes a first substrateon which a large number of pixel circuits including active elements (forexample, transistors) are arranged and formed in a matrix with arow-column configuration and a second substrate arranged so as to opposethe first substrate with a predetermined space therebetween. The spacebetween the first substrate and the second substrate is kept to apredetermined space by photo spacers arranged and formed at places onthe first substrate. Liquid crystal is sealed between the firstsubstrate and the second substrate. Arrangement and sizes of thecomponents illustrated in FIG. 2 are schematic and do not reflect actualarrangement and the like.

The display region 21 has a matrix (row-column) configuration in which Mrows×N columns of the sub pixels Vpix including liquid crystal layersare arranged. In this specification, a row indicates a pixel row havingN sub pixels Vpix aligned in one direction. A column indicates a pixelcolumn having M sub pixels Vpix aligned in a direction orthogonal to therow extension direction. Values of M and N are determined in accordancewith a resolution in the vertical direction and a resolution in thehorizontal direction. In the display region 21, scan lines 24 ₁, 24 ₂,24 ₃, . . . , and 24 _(M) are arranged for the respective rows along anH direction and signal lines 25 ₁, 25 ₂, 25 ₃, . . . , and 25 _(N) arearranged for the respective columns along a V direction in an array of Mrows and N columns of the sub pixels Vpix. Hereinafter, in theembodiment, the scan lines 24 ₁, 24 ₂, 24 ₃, . . . , and 24 _(M) may berepresentatively expressed as scan lines 24, and the signal lines 25 ₁,25 ₂, 25 ₃, . . . , and 25 _(N) may be representatively expressed assignal lines 25. In the embodiment, any three scan lines of the scanlines 24 ₁, 24 ₂, 24 ₃, . . . , and 24 _(M) are expressed as scan lines24 _(m), 24 _(m+1), and 24 _(m+2) (m is a natural number satisfyingm≤M−2), and any three signal lines of the signal lines 25 ₁, 25 ₂, 25 ₃,. . . , and 25 _(N) are expressed as signal lines 25 _(n), 25 _(n+1),and 25 _(n+2) (n is a natural number satisfying n≤N−2).

The drive element 3 is a circuit mounted on the glass substrate of theimage output panel by chip on glass (COG), for example. The driveelement 3 is coupled to a controller 100 through a flexible printedcircuits (FPC) (not illustrated). The controller 100 is a circuitconfigured to control operations of the display unit 2 and the lightsource unit 6. To be specific, the controller 100 functions as, forexample, a display controller 101 and a light source controller 102. Thedisplay controller 101 outputs pixel signals for individually drivingthe sub pixels Vpix constituting the pixels Pix. The pixel signal is asignal provided by combining individual gradation values of, forexample, red (R), green (G), blue (B), and white (W), which will bedescribed later, and the color types and the number of colorscorresponding to the gradation values constituting the pixel signal areoptionally determined. The display controller 101 has a function ofcontrolling output gradation values of some or all of the pixels basedon the light emission amounts of light sources 61 that are controlled bythe light source controller 102. The light source controller 102controls operations of the light sources 61 based on a display outputimage of the display unit 2. To be specific, the light source controller102 individually controls the operations of the light sources 61constituting the light source unit 6. The controller 100 may have afunction of outputting various types of signals (for example, a masterclock, a horizontal synchronization signal, and a verticalsynchronization signal) that are used for operations of the display unit2. Configurations for outputting the various types of signals may beseparately provided.

In the embodiment, the light source controller 102 employswhat-is-called one-frame delay control of controlling the operations ofthe light sources 61 based on the pixel signals output from the displaycontroller 101 for one preceding frame. The one-frame delay control canomit a buffer for holding the pixel signals, the buffer being necessarywhen the operations of the light sources 61 are tried to be controlledin the same frame as the pixel signals. The operations of the lightsources 61 may be controlled in the same frame as the pixel signals byproviding the buffer.

The display unit 2 is coupled to an external input power supply (notillustrated) and the like. Electric power necessary for the operationsof the display unit 2 is supplied from the external input power supply.

To be more specific, the drive element 3 operates the display unit 2 inaccordance with various signals received from the controller 100, forexample. The controller 100 outputs, to the drive element 3, forexample, the master clock, the horizontal synchronization signal, thevertical synchronization signal, the pixel signals, and a driveinstruction signal for the light source unit 6. The drive element 3functions as a gate driver and a source driver based on these signalsand the like. At least one of the gate driver and the source driver orboth of them may be formed on a substrate using thin film transistors(TFT), which will be described later. In this case, it is sufficientthat at least one of the gate driver and the source driver or both ofthem is(are) electrically coupled to the drive element 3. The sourcedriver and the gate driver may be electrically coupled to differentdrive elements 3 or the same drive element 3.

The gate driver latches digital data by a unit of one horizontal periodin accordance with the horizontal synchronization signal insynchronization with the vertical synchronization signal and thehorizontal synchronization signal. The gate driver sequentially outputsthe latched digital data for one line as a vertical scan pulse andsupplies it to each of the scan lines 24 (scan line 24 ₁, 24 ₂, 24 ₃, .. . , and 24 _(M)) in the display region 21, thereby sequentiallyselecting the sub pixels Vpix row by row. The gate driver sequentiallyoutputs the digital data to each of the scan lines 24 ₁, 24 ₂, 24 ₃, . .. , and 24 _(M) in the row direction from one end side to the other endside of the display region 21, for example. The gate driver can alsosequentially output the digital data to each of the scan lines 24 _(M),. . . in the row direction from the other end side to one end side ofthe display region 21.

The source driver receives data for pixel driving that is generatedbased on the pixel signals, for example. The source driver writes,through the signal lines 25 (signal lines 25 ₁, 25 ₂, 25 ₃, . . . , and25 _(N)), the data for pixel driving to the sub pixels Vpix in a rowselected by vertical scanning by the gate driver in units of a subpixel, in units of a plurality of sub pixels, or in one unit of all thesub pixels.

Known examples of the driving method of the liquid crystal display panelinclude driving methods of line inversion, dot inversion, and frameinversion. The line inversion is a driving method of inverting thepolarities of video signals at a time cycle of 1H (H is a horizontalperiod) corresponding to one line (one pixel row). The dot inversion isa driving method of alternately inverting the polarities of videosignals for sub pixels adjacent to each other in two intersectingdirections (for example, row and column directions). The frame inversionis a driving method of inverting, at a time, video signals to be writtento all the sub pixels Vpix for each frame corresponding to one screenwith the same polarity. The display unit 2 may employ any one of thedriving methods described above.

In explanation of the embodiment, the M scan lines 24 ₁, 24 ₂, 24 ₃, . .. , and 24 _(M) may be referred to as the scan lines 24 when they arecollectively handled. The scan lines 24 _(m), 24 _(m+1), and 24 _(m+2)in FIG. 3 are a part of the M scan lines 24 ₁, 24 ₂, 24 ₃, . . . , and24 _(M). The N signal lines 25 ₁, 25 ₂, 25 ₃, . . . , and 25 _(N) may bereferred to as the signal lines 25 when they are collectively handled.The signal lines 25 _(n), 25 _(n+1), and 25 _(n+2) in FIG. 3 are a partof the N signal lines 25 ₁, 25 ₂, 25 ₃, . . . , and 25 _(N).

Wiring such as the signal lines 25 supplying the pixel signals to TFTelements Tr of the sub pixels Vpix and the scan lines 24 driving therespective TFT elements Tr is formed in the display region 21. Asdescribed above, the signal lines 25 extend in a plane parallel to thesurface of the above-mentioned glass substrate and supply, to the subpixels Vpix, the data for pixel driving generated based on the pixelsignals for outputting images. The sub pixels Vpix include the TFTelements Tr and liquid crystal elements LC. The TFT elements Tr areformed by thin film transistors and, in this example, are formed byn-channel metal oxide semiconductor (MOS)-type TFTs. One of a source anda drain of each TFT element Tr is coupled to the signal line 25, a gatethereof is coupled to the scan line 24, and the other of the source andthe drain thereof is coupled to one end of the liquid crystal elementLC. One end of each liquid crystal element LC is coupled to the other ofthe source and the drain of the TFT element Tr, and the other endthereof is coupled to a common electrode COM. A drive electrode driver(not illustrated) applies a drive signal to the common electrodes COM.The drive electrode driver may be one structure of the drive element 3or an independent circuit.

Each scan line 24 couples the sub pixel Vpix to the other sub pixelsVpix belonging to the same row in the display region 21. The scan lines24 are coupled to the gate driver and receive supply of vertical scanpulses of scan signals from the gate driver. Each signal line 25 couplesthe sub pixel Vpix to the other sub pixels Vpix belonging to the samecolumn in the display region 21. The signal lines 25 are coupled to thesource driver and receive supply of the pixel signals from the sourcedriver. Each common electrode COM couples the sub pixel Vpix to theother sub pixels Vpix belonging to the same column in the display region21. The common electrodes COM are coupled to a drive electrode driver(not illustrated) and receive supply of the drive signal from the driveelectrode driver.

The gate driver applies the vertical scan pulse to the gates of the TFTelements Tr of the sub pixels Vpix through one of the scan lines 24,thereby sequentially selecting, as an image output target, one row (onehorizontal line) of the sub pixels Vpix formed in a matrix with therow-column configuration in the display region 21. The source driversupplies, through the signal lines 25, the pixel signals to the subpixels Vpix included in one horizontal line that the gate driversequentially selects. Image output of one horizontal line is performedin these sub pixels SPix in accordance with the supplied pixel signals.

As described above, in the display unit 2, the gate driver drives tosequentially scan the scan line 24, thereby sequentially selecting onehorizontal line. The source driver supplies the pixel signals to the subpixels Vpix belonging to one horizontal line through the signal lines25, whereby image output is performed in the display unit 2 on ahorizontal line basis. In this image output operation, the driveelectrode driver applies the drive signal to the common electrodes COMcorresponding to the one horizontal line.

The display region 21 has a color filter. The color filter includes alattice-shaped black matrix 76 a and openings 76 b. The black matrix 76a is formed to cover the outer circumferences of the sub pixels Vpix asillustrated in FIG. 3. In other words, the black matrix 76 a is arrangedat boundaries between the two-dimensionally arranged sub pixels Vpix,thereby having the lattice shape. The black matrix 76 a is made of amaterial having high light absorptivity. The openings 76 b are openingsformed by the lattice shape of the black matrix 76 a and arranged atpositions corresponding to the sub pixels Vpix.

The openings 76 b have color regions corresponding to the sub pixelsVpix of three colors (for example, red (R), green (G), and blue (B)) orfour colors. Specifically, the openings 76 b have color regions coloredwith three colors of red (R), green (G), and blue (B) as an example of afirst color, a second color, and a third color and a color region of afourth color (for example, white (W)). In the color filter, the colorregions colored with the three colors of red (R), green (G), and blue(B) are periodically arrayed in the openings 76 b, for example. When thefourth color is white (W), the openings 76 b of white (W) are notcolored by the color filter. When the fourth color is another color, theopenings 76 b are colored by the color filter with the color employed asthe fourth color. In the embodiment, the color regions of four colors asone set: the three colors of R, G, and B and the fourth color (forexample, white (W)), are made to correspond to the sub pixels Vpixillustrated in FIG. 3 to form one pixel Pix. The pixel signal suppliedto one pixel Pix in the embodiment corresponds to output of one pixelPix including the sub pixels Vpix of red (R), green (G), blue (B), andthe fourth color (white (W)). In explanation of the embodiment, red (R),green (G) , blue (B), and white (W) may be simply referred to as R, G,B, and W, respectively. When the pixel Pix includes the sub pixels Vpixof equal to or less than two or equal to or more than five colors, it issufficient that digital data corresponding to the number of colors issupplied based on original image data.

The color filter may be colored with a combination of other colors aslong as it is colored with different colors. In general, in the colorfilter, the luminance in the color region of green (G) is higher thanthose of the color region of red (R) and the color region of blue (B).When the fourth color is white (W), light-transmissive resin may be usedfor the color filter to produce white.

When the display region 21 is viewed from the direction orthogonal tothe front, the scan lines 24 and the signal lines 25 are arranged inregions overlapping with the black matrix 76 a of the color filter. Inother words, the scan lines 24 and the signal lines 25 are hidden behindthe black matrix 76 a when viewed from the direction orthogonal to thefront. In the display region 21, regions in which the black matrix 76 ais not arranged correspond to the openings 76 b.

FIG. 4 is a schematic view of the display device capable of localdimming. A display device enabling the local dimming includes a displaypanel P capable of changing light transmittance in accordance with adisplay image, a plurality of light sources LM, and a plurality ofreflectors R. The light sources LM are arranged on the opposite side(rear surface side) to a display surface of the display panel P whenviewed from the display surface side. The light sources LM are arrayedin a two-dimensional matrix form with a row-column configuration. Thelight sources LM individually emit light to the display panel P. Thereflectors R are provided for the respective light sources LM. Eachreflector R is a cylindrical member that broadens toward the displaypanel P side from the light source LM side. The light source LM isarranged on a first end side of the cylinder of the reflector R, and thedisplay panel P is arranged on a second end side thereof. The reflectorR reflects the light of the light source LM by the inner surface thereofand guides the light toward the display panel P side.

The reflectors R are provided in a two-dimensional matrix form with arow-column configuration on the rear surface side of the display panel Pin a manner similar to the light sources LM. The reflectors R areintegrally formed to constitute a reflector unit RU.

FIG. 5 is a diagram illustrating aspects and arrangement of the displayunit 2, the light source unit 6, a light guiding unit 7, and thediffusion plate 9. In the following explanation, the direction of thelight L emitted to the display unit 2 along the optical axis IL is a Zdirection. One of two directions along a plane orthogonal to the Zdirection is an X direction, and the other thereof is a Y direction. TheX direction is a direction identical to the H direction. The Y directionoverlaps with the V direction in a plan view when viewed from the Zdirection. In the embodiment, the optical axis IL is set by arrangementof a substrate 612 (see FIG. 14) included in the light source 61. To bespecific, each light source 61 is designed to output the light L from alight emitting element (for example, a light emitting diode (LED) 611)provided on the plate surface of the substrate 612 such that thedirection orthogonal to the substrate 612 is the optical axis IL. Thatis to say, the optical axis IL is set to be the Z direction by arrangingthe substrate 612 along the X-Y plane.

The display device 1 in the embodiment includes the light guiding unit 7functioning as the reflector unit RU. The light guiding unit 7 has aplurality of light guiding members 700. The light guiding members 700function as the reflectors R. That is to say, the light guiding members700 are provided as cylindrical members extending toward the displayunit 2 from the light sources 61 and covering the peripheries of theoptical axes IL of the light L from the light sources 61. The lightguiding members 700 reflect the light L from the light sources 61 by theinner surfaces thereof and guide it to the display unit. FIG. 5illustrates four light guiding members 700 aligned along an outputsurface 701 formed by the edges of output ports from which the lightfrom the light sources 61 is emitted. In FIG. 5 and other figures,different reference numerals are assigned to the light guiding members700 column by column like light guiding members 711, 721, 731, and 741in order to distinguish the four light guiding members 700 provided atdifferent positions from one another. The output surface 701 is along afirst direction Ia. The first direction Ia is inclined with respect tothe Y direction. The light source 61 is arranged at a first end of thelight guiding member 700. The first end of each light guiding member 700is an end portion on the opposite side to the output surface 701.Hereinafter, a second end of the light guiding member 700 indicates anend portion on the output surface 701 side. The first ends of the lightguiding members 700 at which the light sources 61 are arranged are alongthe X-Y plane. The light sources 61 function as the light sources LM.The display unit 2 functions as the display panel P.

At a first end of the light guiding unit 7, the first ends of the lightguiding members 700 aligned along the first direction Ia form step-wiselevel differences. In FIG. 5, the positions of the first ends of thelight guiding members 700 aligned along the first direction Ia aredisplaced to the output direction (upward) of the light from the lightsources 61, that is, to the second end in a stepwise manner in the orderof the light guiding members 711, 721, 731, and 741. In other words, thefirst end of the light guiding member 721 and the light source 61provided at the light guiding member 721 are located closer to thesecond end than the first end of the light guiding member 711 and thelight source 61 provided at the light guiding member 711 are. The firstend of the light guiding member 731 and the light source 61 provided atthe light guiding member 731 are located closer to the second end thanthe first end of the light guiding member 721 and the light source 61provided at the light guiding member 721 are. The first end of the lightguiding member 741 and the light source 61 provided at the light guidingmember 741 are located closer to the second end than the first end ofthe light guiding member 731 and the light source 61 provided at thelight guiding member 731 are.

A power supply unit 62 is provided on the first end side of the lightguiding unit 7. Step-wise level differences corresponding to the lightsources LM arranged so as to form the step-wise level differences asdescribed above are formed on the light guiding unit 7 side of the powersupply unit 62. The light sources 61 provided on the first end side ofthe respective light guiding members 700 are coupled to the surface onthe light guiding unit 7 side of the power supply unit 62 to receivesupply of electric power from the power supply unit 62 and control ofthe light amounts from the controller 100. Although FIG. 5 illustrates aspace between the power supply unit 62 and the light guiding unit 7, thespace is not actually provided. That is to say, the light sources 61provided on the first end side of the respective light guiding members700 are arranged on any of the levels on the light guiding unit 7 sideof the power supply unit 62. The surfaces of a first level 611, a secondlevel 621, a third level 631, and a fourth level 641 on the lightguiding unit 7 side, which are the surfaces of the respective levels onthe light guiding unit 7 side, are along the X-Y plane. The light source61 provided at the light guiding member 711 is placed on the first level611. The light source 61 provided at the light guiding member 721 isplaced on the second level 621. The light source 61 provided at thelight guiding member 731 is placed on the third level 631. The lightsource 61 provided at the light guiding member 741 is placed on thefourth level 641.

The display unit 2 and the diffusion plate 9 are arranged on the outputsurface 701 side of the light guiding unit 7. The diffusion plate 9 isinterposed between the display unit 2 and the light guiding unit 7. Aplate surface 201 of the display unit 2 is along a second direction Ib.A plate surface 901 of the diffusion plate 9 is along a third directionIc. The second direction Ib and the third direction Ic are inclined withrespect to the Y direction. In the embodiment, the inclinationdirections and inclination angles of the first direction Ia, the seconddirection Ib, and the third direction Ic with respect to the Y directionare identical. At least one of the first direction Ia, the seconddirection Ib, and the third direction Ic may be different from anotherdirection. In this case, difference between the inclination angle of thesecond direction Ib with respect to the Y direction and the inclinationangle of the third direction Ic with respect to the Y direction isdesirably within a range of ±2%. When one thereof (the inclination angleof the second direction Ib with respect to the Y direction or theinclination angle of the third direction Ic with respect to the Ydirection) is 100%, the “2%” is a ratio of the other one.

FIG. 6 is a perspective view of the light guiding unit 7. FIG. 7 is anX-Z plan view of the light guiding unit 7. The light guiding unit 7 hasthe light guiding members 700 aligned along the X direction. FIG. 6 andFIG. 7 illustrate a row of the light guiding members 700 that is formedby eight light guiding members 700 aligned in the X direction, likelight guiding member 711, 712, 713, 714, 715, 716, 717, and 718. Also atpositions of light guiding members 721, 731, and 741 in columnsdiffering from that of the light guiding member 711, eight light guidingmembers 700 aligned in the X direction form the rows of the lightguiding members 700, like light guiding member 721, . . . , and 728,light guiding members 731, . . . , and 738, and light guiding members741, . . . , and 748. The number of light guiding members 700 alignedalong the X direction may be equal to or less than seven or equal to ormore than nine. Similarly, the number of light guiding members 700aligned along the first direction Ia may be equal to or less than threeor equal to or more than five. The number and arrangement of the lightsources 61 correspond to the number and arrangement of the light guidingmembers 700.

The output surface 701 described with reference to FIG. 5 is the surfacealong the edges of the second ends of the light guiding members 700arrayed in the row and column directions (see FIG. 6 and FIG. 7). Asdescribed above, the output surface 701 is along the first direction Iaand is inclined with respect to the Y direction. In FIG. 6, theinclination angle of the first direction Ia with respect to the Ydirection is an angle θa. The angle θa is, for example, 13°. The angleis however merely an example, is not limited thereto, and can beappropriately changed.

FIG. 8 is an X-Y plan view of the light guiding unit 7. FIG. 9 is across-sectional view cut along line J-J in FIG. 8. The cross section cutalong line J-J is a cross section of the row of the light guidingmembers 700 that is formed by the light guiding members 721, . . . , and728 when cut along the X-Z plane, and the same applies to cross sectionsof the other rows of the light guiding members 700 when cut along theX-Z plane. FIG. 10 is a cross-sectional view cut along line K-K in FIG.8. The cross section cut along line K-K is a cross section of the columnof the light guiding members 700 that is formed by the light guidingmembers 714, . . . , and 744 when cut along the Y-Z plane, and the sameapplies to cross sections of the other columns of the light guidingmembers 700 when cut along the Y-Z plane.

The light guiding member 700 has a reflective unit 750. The reflectiveunit 750 covers the inner surface of the cylinder formed by the lightguiding member 700. The reflective unit 750 is provided in order tofurther increase the reflectance of the light L from the light source61. It is sufficient that the reflective unit 750 is a member havinghigher reflectance of the light L than that of resin as a material ofthe light guiding member 700 in the embodiment. For example, thereflective unit 750 may be a sheet-like reflective member that is bondedto the inner surface of the light guiding member 700, may be metal orcompound that firmly adheres to the inner surface of the light guidingmember 700 by a method of coating, deposition, or the like, or may be amember provided on the inner side of the light guiding member 700 byanother method.

The reflective unit 750 includes a first inner surface portion 751 and asecond inner surface portion 752 opposing each other in the Y directionand a third inner surface portion 753 and a fourth inner surface portion754 opposing each other in the X direction. The extension length of thesecond inner surface portion 752 in the Z direction is larger than thatof the first inner surface portion 751. Difference in the extensionlength in the Z direction between the first inner surface portion 751and the second inner surface portion 752 is set depending on the firstdirection Ia as the upward direction toward the first inner surfaceportion 751 from the second inner surface portion 752. The third innersurface portion 753 and the fourth inner surface portion 754 arelinearly symmetric with each other with respect to the Y direction. Thatis to say, a straight line connecting the first end side of the thirdinner surface portion 753 and the first end side of the fourth innersurface portion 754 is along the X direction. A straight line connectingthe second end side of the third inner surface portion 753 and thesecond end side of the fourth inner surface portion 754 is along the Xdirection. A straight line connecting the first end side of the firstinner surface portion 751 and the first end side of the second innersurface portion 752 is along the Y direction.

A joint between the first inner surface portion 751 and the second innersurface portion 752, a joint between the second inner surface portion752 and the third inner surface portion 753, a joint between the thirdinner surface portion 753 and the fourth inner surface portion 754, anda joint between the fourth inner surface portion 754 and the first innersurface portion 751 in the embodiment have curved shapes. These jointsmay however be joints forming angles, and specific shapes thereof can beappropriately changed. The same applies to the shapes of the lightguiding members 700 located on the outer circumference sides of thesejoints.

In the embodiment, the resin as the material of the light guidingmembers 700 is black resin. The black resin absorbs light more easilythan resin of the other colors does. The light L from the light sources61 can therefore be hampered from passing through the light guidingmembers 700 and leaking to the outside.

Each light guiding member 700 broadens toward a front end portion T froma bottom portion B. In other words, the light guiding member 700 hassuch a shape that a distance between the inner surfaces and the opticalaxis IL increases toward the output surface 701 side (the second endside) from the light source 61 side (the first end side). Such a shapefunctions as a shape for making the reflection direction of the light Lfrom the light source 61 be along the Z direction and can be used as adraft angle when the light guiding member 700 is formed by injectionmolding. In the wall surfaces forming the cylinder of the light guidingmember 700, the thickness of the front end portion T located relativelyclose to the second end side is smaller than the thickness of the bottomportion B located relatively closed to the first end side. Thisconfiguration can further reduce the probability that a sink mark isgenerated in the front end portion T formed as a larger cylindricalframe body than the bottom portion B.

FIG. 11 is a Y-Z plan view of the light guiding member 700. FIG. 12 andFIG. 13 are X-Z plan views of the light guiding member 700. Each lightguiding member 700 includes a first wall surface portion 761 and asecond wall surface portion 762 opposing each other in the Y directionand a third wall surface portion 763 and a fourth wall surface portion764 opposing each other in the X direction. In a manner similar to therelation between the second inner surface portion 752 and the firstinner surface portion 751, an extension length Z2 of the second wallsurface portion 762 in the Z direction is larger than an extensionlength Z1 of the first wall surface portion 761 in the Z direction.Difference in the extension length in the Z direction between the firstwall surface portion 761 and the second wall surface portion 762 is setdepending on the first direction Ia. The third wall surface portion 763and the fourth wall surface portion 764 are linearly symmetric with eachother with respect to the Y direction in a manner similar to therelation between the third inner surface portion 753 and the fourthinner surface portion 754. That is to say, a straight line connectingthe first end side of the third wall surface portion 763 and the firstend side of the fourth wall surface portion 764 is along the Xdirection. A straight line connecting the first end side of the firstwall surface portion 761 and the first end side of the second wallsurface portion 762 is along the Y direction. That is to say, asdescribed above, the first end side of the light guiding member 700 isalong the X-Y plane. A straight line connecting the second end side ofthe third wall surface portion 763 and the second end side of the fourthwall surface portion 764 is along the X direction. FIG. 12 is a viewwhen viewed from the first wall surface portion 761 side. FIG. 13 is aview when viewed from the second wall surface portion 762 side.

A first intermediate portion P3 of the first wall surface portion 761and a first intermediate portion P4 of the second wall surface portion762 in FIG. 11 has the same distance to the optical axis IL. Incontrast, an interval Z3 between the first end of the light guidingmember 700 and the first intermediate portion P3 in the Z direction isdifferent from an interval Z4 between the first end of the light guidingmember 700 and the first intermediate portion P4 in the Z direction. InFIG. 11, Z4>Z3 is satisfied. When a line connecting the firstintermediate portion P3 and the first intermediate portion P4 is drawnon the third wall surface portion 763, the line has an inclination in adirection identical to the first direction Ia with respect to the Zdirection. This indicates that a curvature of the shape that broadensfrom the first end side of the light guiding member 700 toward thesecond end side thereof is different between the first wall surfaceportion 761 and the second wall surface portion 762. A relation betweena second intermediate portion P5 of the first wall surface portion 761and a second intermediate portion P6 of the second wall surface portion762 and a relation between a third intermediate portion P7 of the firstwall surface portion 761 and a third intermediate portion P8 of thesecond wall surface portion 762 are similar to the relation between thefirst intermediate portion P3 and the first intermediate portion P4. Inthis manner, in the light guiding member 700, the portions opposing eachother at positions orthogonal to the optical axis IL are not uniform incurvature.

The reflective unit 750 provided on the inner surfaces of the lightguiding member 700 also has difference in curvature due tonon-uniformity of the curvature in the inner surfaces opposing eachother at positions orthogonal to the optical axis IL in a manner similarto the light guiding member 700. The difference in the curvature is setso as to reduce the difference in reflection of the light L due to thedifference in the distance from the first end to the second end betweenthe first inner surface portion 751 and the second inner surface portion752. That is to say, the difference in the curvature is set such thatluminance distribution of the light L emitted from the output port iscloser to uniformity between the first inner surface portion 751 sideand the second inner surface portion 752 side with the optical axis ILinterposed therebetween.

A distance to the optical axis IL does not need to be equal between thesecond end P1 of the first wall surface portion 761 and the second endP2 of the second wall surface portion 762. The optical axis IL may bedisplaced in the Y direction from the center of the output port at thesecond end of the light guiding member 700 that is surrounded by theinner surfaces of the first wall surface portion 761, the second wallsurface portion 762, the third wall surface portion 763, and the fourthwall surface portion 764, that is, the first inner surface portion 751,the second inner surface portion 752, the third inner surface portion753, and the fourth inner surface portion 754. For example, the opticalaxis IL may be displaced to the first inner surface portion 751 sidewith respect to a line (intermediate line) along the Z direction fromwhich distances to the second end P1 and the second end P2 in the Ydirection are equal to each other. As for the X direction, the opticalaxis IL is desirably located on a line with respect to which the thirdinner surface portion 753 and the fourth inner surface portion 754 arelinearly symmetric with each other.

FIG. 14 is a perspective view of the light source 61. Each light source61 has the LED 611, the substrate 612, and a diffusion member 613. TheLED 611 is a light emitting diode emitting white light, for example. TheLED 611 is on with electric power supplied from the power supply unit 62and emits light. The substrate 612 is a substrate on which wiring thatis to be coupled to the LED 611 is mounted. The substrate 612 isinstalled on any of the levels of the power supply unit 62 to couple theLED 611 and the power supply unit 62. With reference to a positionalrelation between the first end and the second end of the light guidingmember 700, the substrate 612 is located on the first end side of theLED 611. The LED 611 emits light to the second end side. The diffusionmember 613 is a light guiding member having translucency and provided soas to cover the second end sides of the LED 611 and the substrate 612and has the same configuration as that of the diffusion plate 9. Thediffusion member 613 diffuses the light from the LED 611 in a planarform and outputs it from the second end side.

In the embodiment, X-Y planar shapes of the substrate 612 and thediffusion member 613 are rectangular shapes each having four sidesincluding two sides opposing each other along the X direction and theother two sides opposing each other along the Y direction. The innershape of the cylinder at the first end of the light guiding member 700corresponds to the outer shape of the X-Y planar shape of the lightsource 61. Thus, the light source 61 has a light emission surface havinga rectangular shape. The light guiding member 700 is formed to have ashape along the X-Y plane that has four sides (the first wall surfaceportion 761, the second wall surface portion 762, the third wall surfaceportion 763, and the fourth wall surface portion 764) along the foursides of the light emission surface (see FIG. 8).

The substrate 612 in the embodiment is a black substrate on at least thesecond end side. That is to say, the color of the substrate 612 on atleast the side on which the LED 611 is provided is black. The opticalaxis IL from the LED 611 can therefore be hampered from passing throughthe substrate 612 and leaking to the first end side. The substrate 612may be formed such that only the surface of the substrate 612 on thesecond end side before a wiring pattern and the like are formed is blackor a larger area including the surface of the substrate 612 on the firstend side is black.

Although in FIG. 14, one LED 611 is provided in one light source 61, aplurality of LEDs 611 may be provided in one light source 61.

Hereinafter, action effects of the embodiment will be described withreference to FIG. 15. FIG. 15 is a schematic descriptive diagram forexplaining a relation between angles of the plate surface 201 of thedisplay unit 2, the output surface 701, and the plate surface 901 of thediffusion plate 9, and a shape and luminance distribution of an imageoutput from the display device.

In an example in FIG. 15, the output surface 701, the plate surface 201,and the plate surface 901 are provided in states of being inclined inthe first direction Ia, the second direction Ib, and the third directionIc, respectively, with respect to the Y direction as in theabove-mentioned embodiment. In this example, the image VI is viewed as arectangular image in which imbalance of the brightness is not generatedentirely.

In contrast, in a first comparative example in FIG. 15, only the platesurface 201 is inclined in the second direction Ib with respect to the Ydirection whereas the output surface 701 and the plate surface 901 areprovided so as to be along the Y direction. In the first comparativeexample, the image VI is viewed as a trapezoidal image having one sidethe length of which is relatively short and the opposing side the lengthof which is relatively long. The one side corresponds to the side atwhich a distance between the plate surface 201 and the plate surface 901is relatively short, and the opposing side corresponds to the side atwhich the distance between the plate surface 201 and the plate surface901 is relatively long. That is to say, in the first comparativeexample, distortion is generated in the image.

In a second comparative example in FIG. 15, the plate surface 201 isinclined in the second direction Ib with respect to the Y direction, theplate surface 901 is inclined in the third direction Ic with respect tothe Y direction, and the output surface 701 is provided so as to bealong the Y direction. In the second comparative example, the image VIis viewed as an image having a portion on one side that is relativelybrighter and a portion on the opposing side that is relatively darker.The one side of the image corresponds to the side at which the distancebetween the plate surface 201 and the output surface 701 is relativelyshort, and the opposing side of the image corresponds to the side atwhich the distance between the plate surface 201 and the output surface701 is relatively long. That is to say, in the second comparativeexample, imbalance of the brightness is generated in the image.

As described above, in the light guiding member 700, the inner surfacesopposing each other at the positions orthogonal to the optical axis ILare not uniform in curvature. With influences by this, when the opticalaxis is located on the intermediate line of the output surface 701 inthe Y direction, imbalance of the luminance is generated. To bespecific, the luminance of the light emitted from the first wall surfaceportion 761 side with respect to the optical axis IL is significantlyhigher than the luminance of the light emitted from the second wallsurface portion 762 side. Also when the optical axis IL is located at aposition closer to the second wall surface portion 762 (left side inFIG. 11) with respect to the intermediate line, similar imbalance of theluminance is generated.

Shifting the position of the optical axis IL to the first wall surfaceportion 761 side (right side in FIG. 11) with respect to theintermediate line can hinder generation of the imbalance of theluminance. In other words, shifting the position of the optical axis ILto the second end P1 side (right side in FIG. 11) with respect to theintermediate line can hinder generation of the imbalance of theluminance.

As described above, according to the embodiment, the plate surface 201of the display unit 2 is inclined with respect to the X-Y plane.Generation of a ghost due to multiplex projection caused bysuperimposition of the light from the light source and the reflectedlight can be therefore be hindered. The output surface 701 of the lightguiding unit 7 is inclined with respect to the X-Y plane. Theinclination direction of the plate surface 201 with respect to theoptical axis IL along the Z direction is the same as the inclinationdirection of the output surface 701. This can provide the image VI thatis viewed as a rectangular image in which imbalance of the brightness isnot generated entirely. Accordingly, the embodiment can achieve both ofrestraint of the occurrence of a ghost and improvement in displayquality.

Each light guiding member 700 has such a shape that broadens toward theoutput surface 701 side such that the distance between the innersurfaces and the optical axis IL increases toward the output surface 701side from the light source 61 side, and the inner surfaces opposing eachother at the positions orthogonal to the optical axis IL are not uniformin curvature. The difference in the reflection of the light L due to thedifference in the distance from the first end to the second end betweenthe first inner surface portion 751 and the second inner surface portion752 can therefore be reduced by the difference in curvature.

The optical axis IL is displaced from the intermediate line in apredetermined direction. The predetermined direction is a direction(right side in FIG. 11) toward the second end P1 side that is one of thesecond end P1 side and the second end P2 side disposed with theintermediate line interposed therebetween and on which the distancebetween the edge of the output port and the light source 61 isrelatively small due to the inclination in the first direction Ia. Thedifference in the reflection of the light L due to the difference in thedistance from the first end to the second end between the first innersurface portion 751 and the second inner surface portion 752 cantherefore be further reduced.

Each light source 61 has the light emission surface having therectangular shape. The light guiding member 700 is formed to have theshape along the X-Y plane that has the four sides along the four sidesof the light emission surface. The light source unit 6 that ispreferable for illumination of the display unit 2 having the rectangulardisplay region 21 can thereby be provided.

The multiple light sources 61 and the multiple light guiding members 700are provided. The light guiding members 700 are individually providedfor the respective light sources 61. The light sources 61 aligned alongthe first direction Ia are arranged in the stepwise manner. With thisarrangement, the output surfaces of the light L from the light sources61 can be made along the X-Y plane to make the optical axes IL along theZ direction, and the light sources 61 can be arranged along the firstdirection Ia. Arrangement of the light sources 61 for the local dimmingin the direction along the first direction Ia can be achieved.

The light sources 61 are aligned along the X direction. Arrangement ofthe light sources 61 for the local dimming in the X direction cantherefore be achieved.

The diffusion plate 9 that is arranged between the light guiding unit 7and the display unit 2 and diffuses light is included. The displayregion 21 can thereby be uniformly illuminated.

The diffusion plate 9 is inclined in an inclination direction identicalto that of the display unit 2 with respect to the X-Y plane. Thedifference in angle with respect to the X-Y plane between the seconddirection Ib and the third direction Ic is within ±2%. Generation of theimbalance of the brightness in the image VI can thereby be furtherhindered.

The light guiding members 700 are made of black resin. Thus, the light Lfrom the light sources 61 can be hindered from passing through the lightguiding members 700 and leaking to the outside. That is to say, loweringin the display quality due to light leakage can be hindered.

The light guiding members 700 have the reflective units 750 covered bythe members having higher reflectance of the light L than the blackresin. Both of restraint of the light leakage with the black resin andguidance of the light L by the reflective units 750 can therefore beachieved.

The light guiding members 700 are formed such that the thicknesses ofthe front end portions T are smaller than those of the bottom portionsB. This can further reduce the probability that a sink mark is generatedin the front end portions T formed as the large cylindrical frame bodiesin comparison with the bottom portions B.

The light guiding members 700 constituting the light guiding unit 7 havethe same shape. The light guiding members 700 can be manufactured usingthe same mold or the like, and the light guiding members 700 can becombined to form the light guiding unit 7. Accordingly, the lightguiding unit 7 can be manufactured more easily.

The above-mentioned embodiment is merely an example and can beappropriately modified in a range without deviating from the technicalcharacteristics of the present disclosure. For example, although thedisplay unit 2 in the embodiment is a display panel enabling colordisplay, the display unit 2 may be a monochrome display panel. In theembodiment, the light sources 61 and the light guiding members 700 arearranged in a matrix with the row-column configuration. Alternatively,the light sources 61 and the light guiding members 700 may be arrangedin one of the X direction and the first direction Ia or one light source61 and one light guiding member 700 may be provided.

Other action effects provided by the aspect described in the embodimentthat are obvious from description of the present specification or atwhich those skilled in the art can appropriately arrive should beinterpreted to be provided by the present disclosure.

What is claimed is:
 1. A display device comprising: a light sourceconfigured to emit light; a display panel capable of receiving the lightfrom a first surface side and transmitting the light to a second surfaceside; and a light guiding member extending to the first surface side ofthe display panel from the light source and reflecting the light to thedisplay panel, wherein the display panel is inclined with respect to anorthogonal plane orthogonal to an optical axis of the light, wherein thelight guiding member has an output surface framed by an output port ofthe light and inclined with respect to the orthogonal plane, wherein aninclination direction of the display panel with respect to the opticalaxis is identical to an inclination direction of the output surface withrespect to the optical axis, and wherein the light guiding member hassuch a shape that a distance between inner surfaces of the light guidingmember and the optical axis increases toward the first surface side fromthe light source side, and the inner surfaces opposing each other atpositions orthogonal to the optical axis are not uniform in curvature.2. The display device according to claim 1, wherein the optical axis isdisplaced in a predetermined direction from a center of the output porthaving a rectangular shape, and wherein the predetermined direction is adirection along the orthogonal plane and directed toward a side on whicha distance between an edge of the output port and the light source isrelatively small due to inclination of the output surface with respectto the orthogonal plane.
 3. The display device according to claim 1,wherein the light source has a light emission surface having arectangular shape, and wherein the light guiding member is formed tohave a shape that is along the orthogonal plane and has four sides alongfour sides of the light emission surface.
 4. The display deviceaccording to claim 1, wherein a plurality of the light sources and aplurality of the light guiding members are provided, wherein the lightsources aligned in the inclination direction are arranged in a stepwiseform along the inclination direction, and wherein the light guidingmembers are provided for the respective light sources.
 5. The displaydevice according to claim 4, wherein the light sources are aligned alonga direction orthogonal to the optical axis and the inclinationdirection.
 6. The display device according to claim 1, comprising adiffusion plate that is arranged between the light guiding member andthe display panel and diffuses the light.
 7. The display deviceaccording to claim 6, wherein the diffusion plate is inclined in aninclination direction identical to the inclination direction of thedisplay panel with respect to the orthogonal plane, and whereindifference in angle with respect to the orthogonal plane between aninclination angle of the display panel and an inclination angle of thediffusion plate is within ±2%.